I discuss various reflective signaling methods in a previous article “Back-To-Back CD Signal Mirror Method” that can be applied to this new reflective method. Although the glass surface of a cell phone is reflective, it can play a different role in signaling by means of providing a flat surface for a silverized Mylar snack wrapper.

My father used to turn snack bar wrappers inside-out and hung them on a fruit tree to ward off pillaging birds. That memory inspired me to try the same method using my cell phone as a base to hold a silverized snack wrapper as a cover. When held over one eye while using an extended hand as an aiming sight, the sun’s light can be directed to your target to gain attention to persons in the distance in an emergency.

This is a fun project to practice with friends or aimed at a distant reflective surface like a car’s license plate, signal lights, or road signs.

In various conflicts throughout history, most notably Vietnam, a code was developed using “taps” that were used by prisoners of war that could be used by tapping on anything such as a pipe, bar, wall… whatever produced a sound by percussion. This became known as “Tap Code’ or “Knock Code”. It is built on a table of letters called a Polybius square, some of which have slightly different arrangements of the 26 letters that are placed into 25 cells. It was memorized much like we would memorize a multiplication table so that when a combination of taps were heard it would be recognized as a letter.

As you can see by the table it consists of five rows and five columns. Letters are placed in each cell, left to right, top to bottom, with the letters “C” and “K” being interchangeable. The letter “X” was used to break up sentences. Each letter consists of two parts of tapping: first the row number, then the column number. For instance, the letter “S” would be represented by four taps (row) with a slight pause, then three taps (column) followed by a longer pause before introducing the next letter. Using periods to illustrate, it would look like this: …. … I imagine that at first a person would visualize the table while hearing the taps but eventually each combination of taps has a “sound” that becomes recognizable as the letter that it represents.

Unlike Morse Code, Tap Code does not need sustained or differing tones to define a letter. It does not require electronics or light sources. It is completely non verbal and the table is simple enough to create for practice and memorization. I would like to mention that Morse Code has provided a universal “SOS” signal that could be used by tapping like this: … . . . … to gain attention by rescuers.

You can develop this skill of sending and receiving Tap Code by practicing with a friend and eventually teach others as well so that they too can be better prepared for a possible emergency situation where an obscure location or covert communication is needed.

Having spent a good portion of my career in the aerospace/defense industry I have spent some time around parabolic “dish” antennas and have applied this reflective principal to my cell phone on occasions.

Years ago I participated as an Assistant Scout Master at a camp. The parents of one of the Scouts helped transport our troop members and during the week took a vacation along the nearby California coast. At the end of the week they shared this experience with me. At one point the husband needed to make a call but had trouble finding a signal. He asked himself “what would Ken do?”. He looked for a parabolic feature in the landscape and found a rock with a concave surface. He placed the phone at it’s focal point and “bingo!” was able to connect his call.

I couldn’t find a signal at my son’s place so I found a pan and put my phone inside it. Surprisingly, even without a registered signal strength bar showing I was able to connect my call and have the critical items delivered.

This parabolic effect has worked for me and you might keep it in mind if you find yourself in a similar situation. I’m sure that there are other techniques that I would love to hear about so please share your successes in the comments section below so that we may all be better prepared for this eventuality.

I decided to try this method out for myself. Sure enough it works. I noticed some things that you might find helpful. While holding the CD in my hand I noticed that the light coming through the hole created a bright spot on my hand which in turn reflected as a refractive line on the backside mirror. I could shift my hand left or right to center the line over the hole. I could then shift the CD up or down to center the reflected dot into the hole. I used a reflective license plate as a target so that I could see when the light passed over it. The short video above captures my test results.

I have included a photo of a retro-reflector mirror for reference to this signaling method.

Ferro rods come in a variety of sizes, from 1/8″ to 1/2″ in diameter and from 2″ to 4″ in length. When it comes to sparks – bigger is better but there’s something to be said for technique. There are small ferro tips mounted inside “spring strikers” that are used to ignite propane torches. But the smallest ferro rod and unsung hero is the “flint” inside a cigarette lighter.

I collect dry flintwheel lighters to show others how they can still be useful. To best access the sparks that it produces, I remove the wind screen. After experimenting with a wide variety of flintwheel lighters I have found that the “Bic” brand has the largest and most durable flint as compared to the cheap inexpensive imports.

As for illumination, a person can grope in the dark for dropped items or for a door knob or key hole, but light is essential for reading signs or printed material as illustrated in the photo. This image of a flintwheel spark was captured from a video frame at 1/30th of a second. Repeated flashes can be used to navigate in a room or for short distances. Larger ferro rods can be used in an emergency situation for signaling at dusk or in the dark however this usually requires the use of both hands.

Just remember… don’t use a sparking device in a flammable gas environment!

A cavity whistle uses a small hollow over which there is a small hole or opening. A person can blow over the small hole and a high pitched tone can be heard. Many items can be used for a cavity whistle such as a pen cap, bullet shell, a clean cut reed segment or a pinched straw.

The most recent cavity whistle that I have learned about is the cap of an acorn. Cover the open space by placing your thumbs together and bending the upper knuckles over the outer edge. Your thumb tips will naturally spread apart, thus creating a small hole. Place your lips on your knuckles and blow into the hole. With practice you can create an extremely loud sound. Similar cavities for this “bent thumbs” method are small plastic or metal bottle caps for water, soda, beer or motor oil.

Even if you can whistle with your lips, learning to use a cavity whistle is another tool in your signal arsenal.

My wife called his cell phone but was unable to connect, and could only leave a message on the automated voice mail. Remembering a blog that I once wrote “Text Messaging has it’s benefits…” I realized that a text message had the best chance of making the contact that we needed. While I texted we would get repeated calls that lasted a few seconds then silence. Although they were hard to hear and frequently interrupted, we got a sense of their situation. I completed the message and sent the text and bingo! a positive connection was established. I was able to get clear directions on where to meet and I was able to deliver gas and lend assistance in getting the car started and on it’s way to the nearest gas station.

So, remember, that when a regular call fails, text has the special properties of small bandwidth and “message persistence” that can get through when voice transmission fails.

A word of caution: in all cases these fuels should be used outdoors or in a very well ventilated area. It’s best to stay upwind from the smoke and fumes that are produced. Make sure that the vessel holding the fuel is stable, as spilled flammable liquids can have disastrous consequences.

Your car holds many emergency fuels, but other types of vehicles and machines such as boats, planes and tractors can provide similar fuels too. Knowing about these resources in an emergency situation and knowing how to use them could save your life.

So, the point of this blog is to encourage you to “think outside the box” and be open to other fields and areas of interest that might be holding alternate resources for expedient solutions in emergency situations. Who knows, a new product may be discovered for us survival enthusiasts to adopt.